package com.zy.jike.数据结构与算法之美.基本数据结构;

import sun.jvm.hotspot.utilities.GenericArray;

public class DynamicArray<T> {
    private T[] data;
    private int size;

    //根据传入容量,构造Array
    public DynamicArray(int capacity){
        data = (T[]) new Object[capacity];
        size = 0;
    }

    //无参构造方法,默认容量为10
    public DynamicArray(){
        this(10);
    }

    //获取数组容量
    public int getCapacity(){
        return data.length;
    }

    //获取当前元素个数
    public int count(){
        return size;
    }

    //判断数组是否为空
    public boolean isEmpty(){
        return size ==0;
    }

    //修改index位置的元素
    public void set(int index,T e){
        checkIndex(index);
        data[index] = e;
    }

    //查看数组是否包含元素T e
    public boolean contains(T e){
        for (int i=0;i<size;i++){
            if(data[i].equals(e)){
                return true;
            }
        }
        return false;
    }

    //获取对应元素的下标，未找到，返回-1；
    public int find(T e){
        for (int i=0;i<size;i++){
            if(data[i].equals(e)){
                return i;
            }
        }
        return -1;
    }

    //在index位置，插入元素e,
    public void add(int index,T e){
        checkIndexForAdd(index);
        //如果当前元素等于数组容量，则将数组扩容为原来两倍
        if(size == data.length){
            resize(2 * data.length);
        }

        for(int i = size -1;i>=index;i--){
            data[i + 1] = data[i];
        }
        data[index] = e;
        size++;
    }
    // 向数组头插入元素
    public void addFirst(T e) {
        add(0, e);
    }

    // 向数组尾插入元素
    public void addLast(T e) {
        add(size, e);
    }

    //删除index文职的元素，并返回
    public T remove(int index){
        checkIndex(index);

        T ret = data[index];
        for(int i=index + 1;i<size;i++){
            data[i -1] = data[i];
        }
        size--;
        data[size] = null;

        // 缩容
        if (size == data.length / 4 && data.length / 2 != 0) {
            resize(data.length / 2);
        }

        return ret;
    }
    // 删除第一个元素
    public T removeFirst() {
        return remove(0);
    }

    // 删除末尾元素
    public T removeLast() {
        return remove(size - 1);
    }

    // 从数组中删除指定元素
    public void removeElement(T e) {
        int index = find(e);
        if (index != -1) {
            remove(index);
        }
    }
    @Override
    public String toString() {
        StringBuilder builder = new StringBuilder();
        builder.append(String.format("Array size = %d, capacity = %d \n", size, data.length));
        builder.append('[');
        for (int i = 0; i < size; i++) {
            builder.append(data[i]);
            if (i != size - 1) {
                builder.append(", ");
            }
        }
        builder.append(']');
        return builder.toString();
    }


    // 扩容方法，时间复杂度 O(n)
    private void resize(int capacity) {
        T[] newData = (T[]) new Object[capacity];

        for (int i = 0; i < size; i++) {
            newData[i] = data[i];
        }
        data = newData;
    }

    private void checkIndex(int index) {
        if (index < 0 || index >= size) {
            throw new IllegalArgumentException("Add failed! Require index >=0 and index < size.");
        }
    }

    private void checkIndexForAdd(int index) {
        if(index < 0 || index > size) {
            throw new IllegalArgumentException("remove failed! Require index >=0 and index <= size.");
        }
    }
}
